Polysiloxane-based gel-like materials are often used as a semiconductor sealing material that utilizes the excellent electrical insulating properties, heat resistance, cold resistance, and stress relieving properties of the material, and protects a semiconductor from external obstacles such as stress generated from a cooling and heating cycle, heat, moisture, and the like. The favorable stress relieving properties thereof are due to a low elastic modulus of polysiloxane gel and a high compression ratio. On the other hand, high viscosity with regard to various substrates is also provided, derived from the surface properties of the gel-like material.
The aforementioned properties and high transparency of the polysiloxane-based gel-like material have been utilized, and in recent years, application to the field of electronic display elements such as smart devices and the like has been studied. The device has a structure where a film formed from a plurality of layers including an electrode layer, dielectric layer, display layer, and the like is interposed between transparent substrates, and in order to protect the electrode layer and display layer, improve adhesion and pressure-sensitive adhesion between the layers, and form a dielectric layer, a polysiloxane-based gel-like material with high heat resistance, cold resistance, and transparency is expected to function effectively.
In the smart apparatuses, high dielectric properties, high compression ratio, and low compression permanent strain are included in addition to excellent transparency as material properties of the dielectric layer material required in pressure sensors and other sensor applications. In order to enhance the sensor sensitivity, a high electrostatic capacitance under a constant pressure must be achieved, and for this purpose, a high dielectric constant is strongly required in the used material. Furthermore, in order to achieve a high sensitivity even under low pressure, a material with a high compression ratio is preferable. Furthermore, from the perspective of durability and reliability, low compression permanent strain, in other words, high resilience must be exhibited.
In order to enhance the specific permittivity of polysiloxane-based materials, introducing a fluoroalkyl group having a plurality of fluorine atoms on a silicon atom is already known to be effective, and the present inventors also disclosed that an organopolysiloxane cured product containing a fluoroalkyl group has a high specific permittivity, and is useful as a transducer material (Patent Literature 1). However, the organopolysiloxane cured product has an essentially elastomer form, and therefore, the compression ratio cannot be said to be sufficiently high, and high sensor sensitivity is difficult to achieve. Furthermore, an organopolysiloxane composition containing a fluoroalkyl group, selectively adhered to a specific thermoplastic resin is disclosed (Patent Literature 2). A polysiloxane rubber cured product obtained herein has high adhesion to a substrate, and therefore, if pressure is applied from above a glass, plastic, or other substrate, a problem exists where high adhesive properties between the substrate-polysiloxane are an obstacle, and thus the compression ratio is reduced.
On the other hand, a solvent resistant silicone gel composition is disclosed as an organopolysiloxane containing a fluoroalkyl group, where a cured product is gel-like. The material has a branched organopolysiloxane as a primary component, and has characteristics where flexibility is high even at a low temperature. On the other hand, technology with two types of polymers with different degrees of polymerization is not disclosed anywhere. Furthermore, there is neither mention nor suggestion of the dielectric properties, compression, and recovery properties of the cured product, application to a dielectric layer material or display device, and technology of film forming technology. Therefore, an addition curing type organopolysiloxane containing an fluoroalkyl group with excellent transparency, high specific permittivity, and excellent compression and recovery properties, a dielectric layer film containing the organopolysiloxane, and a display device configured from the dielectric layer film have not been reported to date.